TELNET-PROBE(1)

💖 TELNET-PROBE(1) — the lil' telnet-ish port prober 💖

okay so bestie, gather round, because this is telnet-probe from the General Commands Manual and she is lowkey iconic. lightest-weight telnet-like port probe you ever did see. no cap.

✨ NAME ✨

telnet-probe — a lightweight, telnet-like port probe 🎀

🌸 SYNOPSIS 🌸

$PCP_BINADM_DIR/telnet-probe [-cv?]  host port

that's it. that's the whole vibe. host, port, maybe a flag or two, go off 💅

🦋 DESCRIPTION 🦋

so what does she even do? okay so telnet-probe is the girl the pmdashping(1) daemons call when they need to actually connect to random local and remote service-providing daemons, so that response time and service availability info can be obtained. she's the plug. she makes the connection happen so the numbers can be gathered. periodt.

the host and port arguments are required, and they mean exactly the same thing as their telnet(1) equivalents. no reinventing the wheel here, we respect the classics 🫶

now, the -c option makes telnet-probe do a connect(2) only. that means it skips the read(2) and write(2) exercise that would otherwise happen after connecting (more on that below 👇). it's giving "just knock on the door, don't come in."

once the telnet connection is established, here's the whole choreography, in order:

1. telnet-probe reads from stdin until end-of-file 🌈
2. she writes all that input data to the telnet connection ✨
3. next, she reads from the telnet connection until end-of-file, discarding whatever data she receives 💀 (yes, literally discarding it, she does not care, she is unbothered)
4. then telnet-probe exits. bye bestie 👑

⚠️ for this to actually operate successfully, the input you pass through telnet-probe to the remote service must be sufficient to cause the remote service to close the connection once the last line of input has been processed. for example: ending with quit when you're probing SMTP on port 25. if the remote service never closes, she just sits there waiting, and that's not the vibe you want.

by default, telnet-probe will not produce any output. silent. mysterious. main character energy. the only exception is if there's an error — and in that case a diagnostic message can be displayed, but only in verbose mode — and the exit status will be non-zero, indicating a failure. so if you're seeing nothing and the exit code is 0, congrats, it worked 💖

💅 OPTIONS 💅

the available command line options are, and yes, there are only three, she's efficient:

• -c — Connect only, do not read or write. 🎀 just the handshake, nothing more.
• -v — Enable verbose mode. 🔊 now she'll actually tell you things (diagnostics, specifically).
• -? — Display usage message and exit. ❓ the classic "wait, how does this work again" button.

🔥 DIAGNOSTICS 🔥

here's the tea on exit codes:

• if telnet-probe succeeds, then 0 will be returned. ✨ slay.
• if the attempt to establish a connection fails or is terminated, then a non-zero exit status is returned. 💀 check your host, check your port, check your life choices.

🌈 PCP ENVIRONMENT 🌈

environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. iykyk.

on each installation, the file /etc/pcp.conf contains the local values for these variables. 📁

the $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5). so if you wanna point her at a different config, that's your girl. 🧚

👑 SEE ALSO 👑

PCPIntro(1), pmdashping(1), pmie(1), telnet(1), connect(2), read(2) and write(2). go read those next, bestie, they're all part of the lore 📚

and that's the whole page, fr fr. this gem is brought to you by Performance Co-Pilot (PCP), and yes, this is TELNET-PROBE(1) — we literally came full circle. stan a lightweight port probe. bye angel, go probe responsibly 💖✨🎀🦋